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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Cryptographic API.
*
* Cipher operations.
*
* Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
* 2002 Adam J. Richter <adam@yggdrasil.com>
* 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
*/
#include <crypto/scatterwalk.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/scatterlist.h>
static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)
{
void *src = out ? buf : sgdata;
void *dst = out ? sgdata : buf;
memcpy(dst, src, nbytes);
}
void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
size_t nbytes, int out)
{
for (;;) {
unsigned int len_this_page = scatterwalk_pagelen(walk);
u8 *vaddr;
if (len_this_page > nbytes)
len_this_page = nbytes;
if (out != 2) {
vaddr = scatterwalk_map(walk);
memcpy_dir(buf, vaddr, len_this_page, out);
scatterwalk_unmap(vaddr);
}
scatterwalk_advance(walk, len_this_page);
if (nbytes == len_this_page)
break;
buf += len_this_page;
nbytes -= len_this_page;
scatterwalk_pagedone(walk, out & 1, 1);
}
}
EXPORT_SYMBOL_GPL(scatterwalk_copychunks);
void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
unsigned int start, unsigned int nbytes, int out)
{
struct scatter_walk walk;
struct scatterlist tmp[2];
if (!nbytes)
return;
sg = scatterwalk_ffwd(tmp, sg, start);
scatterwalk_start(&walk, sg);
scatterwalk_copychunks(buf, &walk, nbytes, out);
scatterwalk_done(&walk, out, 0);
}
EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy);
/**
* memcpy_sglist() - Copy data from one scatterlist to another
* @dst: The destination scatterlist. Can be NULL if @nbytes == 0.
* @src: The source scatterlist. Can be NULL if @nbytes == 0.
* @nbytes: Number of bytes to copy
*
* The scatterlists can describe exactly the same memory, in which case this
* function is a no-op. No other overlaps are supported.
*
* Context: Any context
*/
void memcpy_sglist(struct scatterlist *dst, struct scatterlist *src,
unsigned int nbytes)
{
unsigned int src_offset, dst_offset;
if (unlikely(nbytes == 0)) /* in case src and/or dst is NULL */
return;
src_offset = src->offset;
dst_offset = dst->offset;
for (;;) {
/* Compute the length to copy this step. */
unsigned int len = min3(src->offset + src->length - src_offset,
dst->offset + dst->length - dst_offset,
nbytes);
struct page *src_page = sg_page(src);
struct page *dst_page = sg_page(dst);
const void *src_virt;
void *dst_virt;
if (IS_ENABLED(CONFIG_HIGHMEM)) {
/* HIGHMEM: we may have to actually map the pages. */
const unsigned int src_oip = offset_in_page(src_offset);
const unsigned int dst_oip = offset_in_page(dst_offset);
const unsigned int limit = PAGE_SIZE;
/* Further limit len to not cross a page boundary. */
len = min3(len, limit - src_oip, limit - dst_oip);
/* Compute the source and destination pages. */
src_page += src_offset / PAGE_SIZE;
dst_page += dst_offset / PAGE_SIZE;
if (src_page != dst_page) {
/* Copy between different pages. */
memcpy_page(dst_page, dst_oip,
src_page, src_oip, len);
flush_dcache_page(dst_page);
} else if (src_oip != dst_oip) {
/* Copy between different parts of same page. */
dst_virt = kmap_local_page(dst_page);
memcpy(dst_virt + dst_oip, dst_virt + src_oip,
len);
kunmap_local(dst_virt);
flush_dcache_page(dst_page);
} /* Else, it's the same memory. No action needed. */
} else {
/*
* !HIGHMEM: no mapping needed. Just work in the linear
* buffer of each sg entry. Note that we can cross page
* boundaries, as they are not significant in this case.
*/
src_virt = page_address(src_page) + src_offset;
dst_virt = page_address(dst_page) + dst_offset;
if (src_virt != dst_virt) {
memcpy(dst_virt, src_virt, len);
if (ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE)
__scatterwalk_flush_dcache_pages(
dst_page, dst_offset, len);
} /* Else, it's the same memory. No action needed. */
}
nbytes -= len;
if (nbytes == 0) /* No more to copy? */
break;
/*
* There's more to copy. Advance the offsets by the length
* copied this step, and advance the sg entries as needed.
*/
src_offset += len;
if (src_offset >= src->offset + src->length) {
src = sg_next(src);
src_offset = src->offset;
}
dst_offset += len;
if (dst_offset >= dst->offset + dst->length) {
dst = sg_next(dst);
dst_offset = dst->offset;
}
}
}
EXPORT_SYMBOL_GPL(memcpy_sglist);
struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
struct scatterlist *src,
unsigned int len)
{
for (;;) {
if (!len)
return src;
if (src->length > len)
break;
len -= src->length;
src = sg_next(src);
}
sg_init_table(dst, 2);
sg_set_page(dst, sg_page(src), src->length - len, src->offset + len);
scatterwalk_crypto_chain(dst, sg_next(src), 2);
return dst;
}
EXPORT_SYMBOL_GPL(scatterwalk_ffwd);
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